A multiphase machine, such as a multiphase electric machine, includes windings with currents that are operated out of phase with each other. For example, a three-phase electric motor may include windings or winding groups that are operated with currents that are 120° out of phase with each other. Multiphase motors may have more than three phases where the phase difference between windings or winding groups is nominally 360°/N, where N is the number of windings or winding groups.
If the rotor in a multiphase machine includes permanent magnets, then the machine is a permanent magnet machine. If the rotor in a multiphase machine includes coils instead of permanent magnets, then the machine is an wound field synchronous machine or induction machine.
A distributed winding multiphase machine is a machine in which stator windings for a given pole or phase span multiple slots or teeth in the inner circumference of the stator. In contrast, a concentrated winding multiphase machine is a machine in which windings for a given pole or phase span only an individual tooth in the inner circumference of the stator. A fractional slot permanent magnet machine is a machine in which stator windings are non-overlapping, i.e., teeth in the inner periphery of the stator are wound such that a winding around one tooth does not extend around another tooth.
Problems with some existing induction and fractional slot permanent magnet machines include the requirement of separate dedicated cooling for the voltage drives that drive the machines. Similarly ingress protection of converters requires the converters to be installed in separate locations from the machine. In some three phase induction machines, converters are maintained in a separate room from the motors to feed three phase power to each motor. Requiring such separate converters increases the cost and complexity of the variable speed drive system as additional installation and component costs add up. Even in variable speed drive system machines with integrated converters, dedicated cooling and converter electronic components that are rated for the entire supply voltage are required. For example, the power supply voltage that is connected across the terminals of a multiphase machine can be 600 volts DC or more. Connecting such a high voltage across the terminals mean that the electronic components within the terminal must be rated for the entire supply voltage. Requiring conventional high voltage components increases the cost of the machine compared to possible alterations.
Accordingly, in light of these difficulties, there exists a need for a multiphase fractional slot concentrated winding machine with an integrated or detachable end mounted multiphase series converter circuit.